1. Field of the Invention
The present invention relates to a self-sealing abutment which divides the variable volume chambers used in fluid operated machines and engines, such as rotary motors, compressors, vacuum pumps, brake systems, mechanical energy accumulator systems and the like, and more particularly the present invention is concerned with a self-sealing abutment which compensates for the wear and tear which take place as a consequence of the frictional engagement between the abutment and the movable members, as well as stationary portions, of such machines, without it being necessary to provide any complementary sealing members to properly seal apart the variable volume chambers which are divided by the abutment.
2. Description of the Prior Art
Fluid operated machines of the type hereinabove cited are known and consist basically of a stator casing defining a substantially cylindrical inner face circumscribing a cylindrical space and within which a rotary, eccentrically mounted piston rotor is rollably located, which upon rolling along the inner face of the stator defines, together with an abutment of the type of the present invention, two variable volume chambers, which, in case for instance of a rotary motor or engine, will respectively become the expansion and compression chambers.
Abutments of this type are plate members and have an upper base portion and lower base portion. A housing projecting out of the stator houses the upper portion including the upper base portion of the diaphragm, the lower base portion of which abuts on the rotary piston in order to maintain a constant contact with the rotary piston. The abutment in combination with the piston rotor, thereby divides the cylindrical space into two variable volume chambers.
It is evident to those skilled in the art that a perfect sealing contact between the abutment and the piston rotor, as well as between the edges of the abutment which are in contact with the housing and the stator casing, should provide a suitably sealed assembly since the variable volume chambers should be perfectly sealed from each other to avoid leakage from one to the other chamber which, if it takes place, reduces considerably the output of the machine.
Within the majority of known fluid operated machines, many suggestions have been made in order to achieve the desired sealing in the most perfect way possible; for instance by providing additional sealing means in conjunction with the edge portions and the lower base portion of the abutment which enter in contact with the stationary housing, the lids of the stator casing and the movable piston rotor. These additional sealing means face the walls of the housing, the stator casing and the piston rotor, and they are usually of very complicated structure. Many sealing members are required since they have to seal several edges, and because they wear quite quickly, they are constantly being improved. The abutment is generally of a poligonal shape, such as rectangular plate.
The maintenance of these sealing members requires a periodical interruption of the operation of the machine for their replacement or at least to check to determine whether their replacement is necessary.
Although these sealing members are being constantly improved, nevertheless such sealing members are required to provide a satisfactory sealing between both variable volume chambers. Although these sealing members are reasonably satisfactory, nevertheless it has to be admitted that these sealing members have a number of drawbacks, bearing in mind that the sealing members must always have a certain resiliency in order to provide a suitable sealing contact, and in addition it is not permitted that there is any play between the sealing members and the walls since such play will immediately produce the undesirable leakage.
In order to achieve a suitable resiliency, it is necessary to apply a constant pressure on the seals against each wall to be sealed. These means usually consist of helicoidal or leaf springs and they must be suitably housed within pertinent recesses to be specially designed therefor. These resilient means are subject to fatigue and to wear, so that their resiliency diminishes and the sealing becomes progressively less and less efficient.